1. Field of the Invention
The present invention generally relates to pot broaching machines and particularly to bottom-loading pot broaching machines having a single mechanism for both loading and unloading the machine.
2. Description of the Prior Art
Machines for broaching the teeth on an external gear as a consequence of a single passage of a work blank through a generally tubular broach are known. The teeth of the broach are located in a pot broach and are usually arranged in longitudinal alignment and are appropriately stepped to perform the required tooth cutting operation. If the gear is a spur gear the teeth are arranged in series extending parallel to the axis of the broach. If the gear is a helical gear the teeth are arranged in helically extending series.
Usually the pot broach is rigidly supported in an elevated position by a goose neck press frame along its vertical axis. Located directly beneath the broach is a piston and cylinder device in which the piston is displaced upwardly during a cutting stroke. A piston rod is connected to the piston and is usually mounted to a work support above the piston which is adapted to receive and carry a gear blank upwardly through the pot broach.
A single passage of the gear blank upwardly through the pot broach results in a complete cutting operation forming the required teeth on the periphery of the gear. The gear is moved upwardly above the upper open end of the broach into a clearance position relative to the broach. It is at this time moved from the work support to a downwardly directed chute.
Automatic means are provided for loading the machine and comprises means for advancing work blanks into a preliminary position directly above the work support. Upward movement of the piston causes the work support to pick up the gear blank and to transport it through the generally tubular broach. Examples of such prior art machines may be seen in U.S. Pat. Nos. 3,656,401 and 3,670,625 and the reader is referred thereto for further details of structure and operation.
The forementioned prior art machines make no provisions for symmetrically mounting the pot broach to a horizontal face of the base structure. As such the stresses from the broaching operation are applied against the vertical mounting support of the press frame and require the support to be extremely rigid and bulky as well as the means used to fasten the pot broach to the mounting surface. Such machines also provide no means for loading and unloading the pot broach with a single mechanical mechanism during one cycle thereof. Separate mechanisms are utilized resulting in more parts and increased machine cost.
Broaching machines are known which mount a broach to a horizontal face of a support structure but these structures are then mounted to a vertical wall or press body. An example of such may be found in U.S. Pat. No. 3,327,589. The side stresses although somewhat alleviated are still not entirely eliminated. Even these machines, however, make no provisions for loading and unloading the broach with a single mechanical mechanism during one cycle thereof.